Standard explained
RCBO Protection Explained
An RCBO combines RCD and MCB protection in one device, giving each circuit both earth-fault and overcurrent protection so a fault only trips that single circuit.
An RCBO (Residual Current Breaker with Overcurrent) combines two functions in a single device: the earth-leakage protection of an RCD and the overcurrent protection of an MCB (miniature circuit breaker).
Why RCBOs are preferred
In a board using shared RCDs, a single earth fault can trip several circuits at once. With an RCBO on each circuit:
- a fault only disconnects the affected circuit, leaving the rest running; and
- fault-finding is simpler, because the tripped device identifies the problem circuit.
This improves both safety and continuity of supply — particularly valuable in commercial premises where nuisance loss of multiple circuits is costly.
On an EICR and upgrades
Upgrading to RCBOs is a common recommendation when improving an older board or adding RCD protection. It is often the tidiest way to bring an installation up to current expectations without wholesale rewiring. See also RCD protection and distribution boards.
Related service
RCD, RCBO & SPD Upgrades
Improved protection through residual-current, overcurrent and surge protective devices.
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Standard explained
AFDDs (Arc Fault Detection Devices) Explained
An AFDD detects dangerous arcing faults in wiring — a common cause of electrical fires — and disconnects the circuit. BS 7671 recommends them for certain premises.
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BS 7671 Explained: The Wiring Regulations
BS 7671 — the IET Wiring Regulations — is the national standard for the safety of electrical installations in the UK, currently the 18th Edition.
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Cable Selection and Sizing Explained
Cable selection under BS 7671 balances current-carrying capacity, installation method, grouping, ambient temperature and voltage drop so conductors run safely.
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Distribution Boards and Consumer Units Explained
Distribution boards (and domestic consumer units) house the protective devices that control and protect each circuit — their condition is central to any EICR.
Learn moreThis article provides general guidance and distinguishes legislation, British Standards and good practice. It is not legal advice. Always confirm the specific duties applying to your property and tenure.